Document DE-C1-42 32 554 discloses a process having these generic features, in which a glass window rests, during application of the trim by the extrusion of a polymer material, on what is called a moulding bed. The latter is located in an edge region of the window on its lower surface and forms, on the perimeter face of the window, an extension of the lower surface of the window. During this time, the edge face and the opposite surface of the window remain free. The trim is formed as a surround along the edge of the free surface of the window. During this time, the edge face and the opposite surface of the window remain free. The trim is formed as a surround along the edge of the free surface of the window and around the edge of the window and it also covers the edge face of the window. Thanks to the moulding bed, the outline of the trim is bounded in a way that it extends level with the other surface (on the side of the moulding bed) of the window. The process is described in the case of monolithic glass windows.
It is also known (from document DE-A1-43 26 650) to fit by extrusion, onto a monolithic glass window, a trim which grips at least the edge of one of the surfaces of the window and its edge face. The trim comes level with the opposite surface of the window. In this process, the extrusion nozzle itself—or an extension placed on it, which is mechanically integral therewith—forms the boundary of the trim cross section on the window surface not covered by the trim. A stationary moulding bed is not necessary in this case.
In a preferred application, the trims are used for fitting windows into the correct position and for sealing them, the windows being adhesively bonded in the window openings of vehicle bodywork. It is not necessary for them, in all cases, to go around the entire perimeter of the windows they can also be provided along just three edges, in special cases along just two edges or even along just one edge and, if necessary, even along just parts of a single edge. These trims must, of course, adhere very strongly to the windows—which are usually made of glass but are also increasingly made of plastic. To guarantee this good adhesion, the substrates must be clean, free of grease, etc. Furthermore, they must usually be coated, in the corresponding regions, with adhesion promoters, also called primers. For each trim material, there is a corresponding primer. In the abovementioned publications, this is discussed exhaustively, the trim also having to adhere to the perimeter face, that is to say to the edge faces or thin edges of the windows.
It must be clearly understood that the process to be described here may be suitable not only for the furnishing of transparent windows with a trim but also used in the case of other substrates of the glazing kind.
Now, when composite glazing (by this is meant, in the case of vehicles, above all the front windows or windscreens, but also increasingly, the side windows or rear windows) formed from several solid panes made of glass and/or synthetic material and from adhesive (organic) interlayers have in particular to be provided with surrounding trims of this kind, blistering and/or debonds may occur when the adhesive layers are closed off to the outside by the trim which adheres thereto. This has been observed in particular in the case of the composite glazing used most often, which is composed of two glass panes and an adhesive layer made of polyvinyl butyral (PVB). In this case, blistering may form in the PVB after the trim has been applied to the composite glazing. Vehicle manufacturers wish above all to incorporate windscreens into the bodywork in as flush and as smooth a manner as possible, without an edge slot, so as to minimize wind resistance, wind noise and also susceptibility to contamination, and to achieve an aesthetically attractive appearance.
Again, a process has already been disclosed (in document DE-A1-42 29 090) in which, in glazing made of composite glass with a PVB adhesive layer, a peripheral edge slot is formed or left free in the plane of the adhesive layer, into which slot a trim with lips, made of a polymer, will be inserted later, so as to protrude from the peripheral edge of the composite glazing. For this purpose, the enveloping surfaces of the said edge slot are coated with an adhesion promoter. The polymer material is then extruded into the edge slot and beyond, in the form of a protruding neck, by means of a suitable gauged extrusion nozzle. However, this process has not proved itself in practice.
Document DE-A1-198 43 843 discloses a window with a trim having a particular cross section, which adheres only to one of the surfaces of this window while covering, however, a slot, with a partially cuneiform cross section, remaining free, in the mounted state, in a window opening of bodywork. This thus also results in a trim fitting approximately flush with the free surface of the window and in a smooth transition with the adjacent surface of the bodywork. In the case of use of this trim, it is necessary, however, during the mounting procedure, to pay greater attention, compared with the abovementioned trims produced by means of a moulding bed, so as to place the trim in the intended final position.